P5 electricity in the home

what is direct current

current that only flows in one direction

what is alternating current

current that repeatedly reverses its direction of flow

what is a mains circuit

has a live wire which is alternately positive and negative every cycle and a neutral wire at 0 volts

what is the peak potential difference of an a.c supply

maximum voltage measured from 0 volts

what is the national grid

the way power stations supply electricity to homes and buildings

what do step up transformers do

increases the potential difference

what do step down transformers do

decreases the potential difference so that it is safe to use in homes

why is plastic used in plugs and plug sockets

good insulator

what is a mains cable made up of

two or three insulated copper wires covered with flexible plastic

what does a three pin plug contain

a live wire which is brown, a neutral wire which is blue and an earth wire which yellow and green

what is the function of the earth wire

connects to the longest pin in the plug and is used to earth the metal case of a mains appliance

what is the power supplied to a device

the energy transferred to it each second

how does a resistor become hot

when the charge flows through a resistor the energy transferred makes it hot

what does a domestic electricity metre measure

how much energy is supplied